We propose to study the effects which daily events have on the sleep patterns of Glaucous-winged Gulls (Larus glaucescens), and to relate modes of sleep to the ecology of these animals. We plan to conduct field and laboratory studies, using biotelemetry which will determine where and when animals are actually asleep. This will provide a basis for describing the patterns of sleep with relation to the animals' habitat and daily events. These data will be analyzed by applying control systems and optimality theory. We are particularly interested in the way sleep patterns are affected by the time available. We will endeavor to provide information on the following questions. Do sleep patterns expand or contract if an animal is kept "busy"? Do environmental factors determine "leisure," defined as that behavior which is abandoned at "busy" times?